SPARK Study - Sympathetic Periarterial Radial Block in Healthy Volunteers

NCT07429292 | Not Yet Recruiting Phase 4 FDA Drug

• 1 other identifier: Pro00119632
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief Summary

The SPARK Study evaluates changes in peripheral sympathetic vasomotor activity following a targeted, ultrasound-guided periarterial sympathetic block of the distal radial artery in healthy volunteers. Autonomic reactivity will be assessed before and after the block using digit-specific pulse-amplitude index and infrared thermography during standardized cold pressor testing.

Conditions

Healthy Volunteers; Sympathetic Activity

Keywords

Sympathetic Block; Radial Artery; Cold Pressor Test; Periarterial block

Outcome Measures

Primary Outcomes (2)

• Pulse amplitude index (PAI)

  Pulse Amplitude Index (PAI) is a noninvasive measure of digital perfusion derived from photoplethysmography (PPG) signals recorded from the fingers. PAI reflects changes in pulse waveform amplitude and serves as an indirect marker of peripheral blood flow and sympathetic vasomotor tone. In this study, PAI will be continuously recorded using digital sensors placed on the index and fifth fingers of the hand undergoing periarterial radial block, as well as the contralateral index finger. Measurements will be obtained at baseline, following cold pressor testing, after the periarterial radial block, and following repeat cold pressor testing. Changes in PAI across time points will be used to assess alterations in peripheral perfusion associated with sympathetic modulation.

  PAI will be measured at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.

• Hand temperature

  Hand temperature is a noninvasive measure of peripheral skin temperature used as an indicator of changes in local blood flow and sympathetic vasomotor activity. In this study, hand temperature will be assessed using infrared thermographic imaging of both hands. Thermal images will be acquired under standardized environmental conditions at baseline, following cold pressor testing, after the periarterial radial block, and following repeat cold pressor testing. Temperature values will be derived from predefined regions of interest on the hands based on arterial territories, and compared across time points to evaluate changes in peripheral perfusion associated with sympathetic modulation.

  Thermal images will be obtained at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.

Secondary Outcomes (3)

• Temporal Changes in Cold Pressor Test-Induced Vasomotor Responses Pre- and Post-Block

  Data will be obtained at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.

• Change in Vasomotor Measures in the Fifth Finger

  PAI and thermal images will be measured at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.

• Change in Vasomotor Measures in the Contralateral Index Finger

  PAI and thermal images will be measured at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.

Study Arms (2)

Left Wrist Block

EXPERIMENTAL

Ultrasound-guided periarterial block with 2% lidocaine at left wrist.

Drug: Lidocaine 2%

Right Wrist Block

EXPERIMENTAL

Ultrasound-guided periarterial block with 2% lidocaine at right wrist.

Drug: Lidocaine 2%

Interventions

Lidocaine 2% DRUG

Small-volume injection (5 mL) of 2% lidocaine around radial artery under ultrasound guidance.

Left Wrist Block; Right Wrist Block

Eligibility Criteria

• Age: 18 Years - 50 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Age 18-50 years
• ASA physical status I-II
• Able to understand and provide informed consent
• Able to comply with study procedures and follow-up
• Two hands with 5 intact digits and no significant upper extremity injury

You may not qualify if:

• Allergy to lidocaine or similar anesthetics
• Allergy to adhesives or ultrasound gel
• Neuromuscular, autonomic, or major vascular disorders affecting upper extremities
• Peripheral neuropathy
• Raynaud's phenomenon or digital ischemia
• Coagulopathy or anticoagulation
• Active skin infection near block site
• Pregnancy
• BMI \> 35 kg/m²
• Inability to tolerate cold exposure
• Any condition interfering with study conduct

Sponsors & Collaborators

• Duke University: lead

Study Sites (1)

Duke University Medical Center

Durham, North Carolina, 27710, United States

Location

Study Officials

• David MacLeod

  Duke University

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: February 18, 2026
• First Posted: February 24, 2026
• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): April 1, 2027
• Last Updated: June 17, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)